My first answer:
Captain was born in 1 9 4 2
He will be 4 6 years old, a canonical age, in 1 9 8 8
In this text, There is only 6 different digits, each of them being used 2 times
This is not exactly a canonical age though...
EDIT :
And my BEST answer:
Captain was born in 1 9 1 3
He will be 9 3 years old, a canonical age, in 2 0 0 6
In this text, There is only 6 different digits, each of them being used 2 times
Now this is a canonical age!